I added new cruiser handlebars to my Serial1. It was a bit of work (with the help of my local bike mechanic), but I managed to replace both brake lines and move the controller outside the handlebars.
In essence, I bought 2 new brake lines, disconnected the control (power/speed device), fished the wire outside of the handlebars (you need to disconnect a purple connector first) then reconnected it outside the handlebars. There is plenty of cable to accomodate any handlebar. I then left the local mechanic to cut the wires and run the new lines externally (he tried to fish them but they have to exit under the light and needed more room than was available. I don't mind the externally routed cables, and my back loves them now that I am sitting more upright. And now I can switch handlebars again if I choose, and do that myself.
My impression is they are cooler than the stock handlebars (sorry S1) and more in line with a Harley look.
I can supply all the parts list I used if anyone is interested.